Support of removable components in a teeth model manufactured by means of CAM

ABSTRACT

A computer-implemented method of generating a virtual model of a set of teeth for manufacturing a physical model of the set of teeth includes providing a virtual model of the set of teeth generating a cavity in said gingival part, into which cavity a removable component fits, where the removable component and the cavity are configured to provide a gap at an interface; and providing for supporting and positioning the removable component in the cavity, wherein the area of contact between the removable component and the cavity wall at the interface is controlled by the shape of the adjoining surfaces of the supporting and positioning and the other of the removable component and the cavity wall.

BACKGROUND OF THE APPLICATION

This invention generally relates to a computer-implemented method of anda system for generating a virtual model of a set of teeth formanufacturing a physical model of the set of teeth, and to a physicalmodel of a set of teeth.

DESCRIPTION OF RELATED ART

When a patient requires a dental restoration, such as crowns, bridges,abutments, or implants, the dentist will prepare the teeth e.g. adamaged tooth is grinded down to make a preparation where a crown can beglued onto. An alternative treatment is to insert implants, such astitanium screws, into the jaw of the patient and mount crowns or bridgeson the implants. After preparing the teeth or inserting an implant thedentist can makes an impression of the upper jaw, the lower jaw and abite registration or a single impression in a double-sided tray, alsoknown as triple trays.

The impressions are sent to the dental technicians who manufacture therestorations. The first step to manufacture the restoration istraditionally to cast the upper and lower dental models from impressionsof the upper and the lower jaw, respectively. The models are usuallymade of gypsum and often aligned in a dental articulator using the biteregistration. The articulator simulates the real bite and chewingmotion. The dental technician builds up the dental restoration insidethe articulator to ensure a nice visual appearance and bitefunctionality. A proper alignment of the cast in the articulator iscrucial for the final restoration.

CAD technology for manufacturing dental restorations is rapidlyexpanding improving quality, reducing cost and facilitating thepossibility to manufacture in attractive materials otherwise notavailable. The first step in the CAD manufacturing process is to createa 3D virtual model of the patient's teeth. This is traditionally done by3D scanning one or both of the dental gypsum models. The 3D replicas ofthe teeth are imported into a CAD program, where the entire dentalrestoration, such as a bridge substructure, is designed. The finalrestoration 3D design is then manufactured e.g. using a milling machine,3D printer, rapid prototyping manufacturing or other manufacturingequipment. Accuracy requirements for the dental restorations are veryhigh otherwise the dental restoration will not be visual appealing, fitonto the teeth, could cause pain or cause infections.

US2009220916 relates to a method for obtaining an accuratethree-dimensional model of a dental impression, said method comprisingthe steps of, scanning at least a part of an upper jaw impression and/ora lower jaw impression, obtaining an impression scan, evaluating thequality of the impression scan, and use the impression scan to obtain athree-dimensional model, thereby obtaining an accurate three-dimensionalmodel of the dental impression.

GB 2122796 discloses a teeth model made from a base (10) of resilientlydeformable rubberised material in the shape of a gum which includes agroove (12) into which pegs of removable individual tooth models (14)are fitted. Each peg (14) includes shoulders (20, 22) and the groove haslateral protrusions (30, 32) for cooperating therewith so that each peghas to be forced into the slot past the protrusions so as to be retainedin position. The natural resilience of the material forming theimitation gum is such as to allow the teeth to be removed by forcingeach tooth out of the slot thereby deforming the protrusion. Each toothis individually removable from the imitation gum, and whilst the visiblecrown of each tooth differs according to normal anatomy the peg of eachtooth is identical thus providing a student with no indication as to thecorrect position for each tooth.

US 2001044092 discloses that a dental model, in particular for practicepurposes, is provided, and has a support plate with recesses forartificial teeth, each of which has a tooth stump that fits into theassociated recess. A gum mass overlaps both the teeth of a row of teethand the recesses. The teeth are each disengageably held on the plate andin their associated recess with friction.

EP1119308B discloses a computer-implemented method for use in developinga course of treatment for an orthodontic patient, the method comprising:obtaining a digital model of a patient's dentition, including a dentalmodel representing the patient's teeth at a set of initial positions anda gingival model representing gum tissue surrounding the teeth; andderiving from the digital model an expected deformation of the gumtissue as the teeth move from the initial positions to another set ofpositions.

It remains a problem to provide an alternative and more efficient methodfor generating a virtual model of a set of teeth comprising a toothwhich requires a restoration and/or a dental treatment, and forgenerating a physical model of the set of teeth comprising such a tooth,such that the dental technician can test the dental restorations, e.g. acrown, on the physical model.

SUMMARY OF THE DISCLOSURE

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth for manufacturing a physical model of the set ofteeth, where the method comprises:

-   -   providing a virtual model of the set of teeth, the model        comprising a gingival part and a tooth configured to be part of        a removable component in the model;    -   generating a cavity in said gingival part, said cavity        comprising a cavity wall, into which cavity the removable        component fits such that an interface between the removable        component and the cavity wall is defined, where the removable        component and the cavity are configured to provide a gap at said        interface; and    -   providing means for supporting and positioning the removable        component in the cavity, where the means for supporting and        positioning are generated on one of said removable component and        said cavity wall such that the means for supporting and        positioning extends across said gap between said removable        component and said cavity wall, such that in a physical model        manufactured from the virtual model, the means for supporting        and positioning support and position the removable component in        the cavity;        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the other of the removable component and the        cavity wall.

The means for supporting and positioning may extend locally across saidgap between said removable component and said cavity wall, i.e. the atsome parts of the circumference of the removable component the gap maybe closed by the means for supporting and positioning, while at otherparts of the circumference, the gap is still open.

In some embodiments, said means for supporting and positioning comprisessupporting elements. In a physical model manufactured from the virtualmodel the supporting elements may extend across said gap between saidremovable component and said cavity wall such that it is the supportingelements which support and position the removable component in thecavity.

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth for manufacturing a physical model of the set ofteeth, where the model comprises one or more teeth preparations, wherethe method comprises:

-   -   generating a virtual model of the set of teeth, where the        virtual model is based on the virtual representation of the set        of teeth;    -   providing that each of the teeth preparations is configured to        be arranged as a removable component in the model, where each        removable component is adapted to fit into a corresponding        cavity in the gingival part of the model;    -   providing means for supporting and positioning each of the        removable components in their corresponding cavities in the        model.

The method further comprises the step of:

-   -   configuring the means for supporting and positioning such that        the area of contact between each removable component and its        corresponding cavity is smaller than the area in which there is        no contact between the removable component and the cavity.

Disclosed is a computer-implemented method for improving a virtual modelof a set of teeth, the method comprising:

-   -   providing a virtual model of a set of teeth, said model        comprising a gingival part and at least one tooth configured to        be part of a removable component, wherein a cavity corresponding        to the removable component is defined in said gingival part,        said cavity comprising a cavity wall, wherein the removable        component is adapted to fit into the cavity such that an        interface between the removable component and the cavity wall is        defined; and    -   improving the virtual model by providing means for supporting        and positioning on one of said removable component and said        cavity wall such that in a physical model manufactured from the        virtual model, the means for supporting and positioning extends        across said gap between said removable component and said cavity        wall such that the means for supporting and positioning support        and position the removable component in the cavity;        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the other of the removable component and the        cavity wall, the means for supporting and positioning allowing        for a controlled reduction of the area of contact in a physical        model manufactured from the improved virtual model compared to a        physical model formed from a virtual model without said means        for supporting and positioning.

Disclosed is a system for generating a virtual model of a set of teethfor manufacturing a physical model of the set of teeth, where the systemcomprises:

-   -   means for generating a virtual model of the set of teeth, where        the virtual model is based on a virtual representation of the        set of teeth;    -   means for providing that at least one tooth is configured to be        arranged as part of a removable component in the model, where        the removable component is adapted to fit into a corresponding        cavity in the gingival part of the model such that an interface        between the removable component and a wall of the cavity is        defined, where the removable component and the cavity are        configured to provide a gap at said interface;    -   means for providing means for supporting and positioning each        removable components in their corresponding cavities in the        model, where the means for supporting and positioning are        provided on one of said removable component and said cavity wall        such that the means for supporting and positioning extends        across said gap between said removable component and said cavity        wall; and    -   means for configuring the means for supporting and positioning        such that the area of contact between the removable component        and the cavity wall at said interface is controlled by the shape        of the adjoining surfaces of the means for supporting and        positioning and the other of the removable component and the        cavity wall.

Disclosed is a physical model of a set of teeth, the physical modelcomprising

-   -   at least one tooth; and    -   a gingival part, wherein a cavity is defined, said cavity        comprising a cavity wall;        wherein said tooth is configured to be part of a removable        component adapted to fit into the cavity in said gingival part        such that an interface between the removable component and the        cavity wall is provided; and wherein on one of said removable        component and said cavity wall comprise means for supporting and        positioning, such that in a physical model manufactured from the        virtual model, the means for supporting and positioning extends        across said gap between said removable component and said cavity        wall such that the means for supporting and positioning support        and position the removable component in the cavity;        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the other of the removable component and the        cavity wall.

Disclosed is a physical model of a set of teeth, wherein the physicalmodel is manufactured from a virtual model generated by the methodaccording to the present invention.

In the context of the present disclosure the phrase “configured to be aremovable component in the model” may refer to the situation where thetooth can be removed from the model (virtual and/or physical) andsubsequently can be inserted into the model again. A tooth may becomprised in the removable component, such that the removable componentmay comprise the tooth and a base. The removable component may consistof a tooth. The removable component may be removable from the gingivalpart of the model. The removable component may be attached to thegingival part of the model by the friction between the removable elementand the cavity wall.

In the context of the present disclosure, the phrase “the base of theremovable component” may be used interchangeably with the phrase “thebottom part of the removable component”.

In the context of the present disclosure, the phrase “the model” may beused in relation to both the physical and the virtual manifestation ofthe set of teeth. In some embodiments, there is a one-to-onerelationship between the virtual model and the physical model of the setof teeth.

In some embodiments, at least part of said means for supporting andpositioning are generated on the removable component such that the areaof contact between the removable component and the cavity wall at saidinterface is controlled by the shape of the adjoining surfaces of themeans for supporting and positioning and the cavity wall.

In some embodiments, at least part of said means for supporting andpositioning are generated on the cavity wall such that the area ofcontact between the removable component and the cavity wall at saidinterface is controlled by the shape of the adjoining surfaces of themeans for supporting and positioning and the removable component.

The means for supporting and positioning generated on the cavity walland/or on the removable component may be an integral part of the unit onwhich they are generated such that e.g. a supporting element becomes apart the structure on which it is generated.

The tolerance with regard to position of and space between the removablecomponent and the gingival part of the model must be very precise, sothat the removable component fits perfect into the cavity of the model.

Consequently, it may be an advantage that by providing the means forsupporting and positioning, the removable components only rest at fewpoints in the cavity and does not rest on or contact the entire innersurface of the cavity. Thus it may be an advantage that it is easier andmore reliably to provide the removable components to fit perfect intothe cavity, without being too firmly attached or too loosely attached.

The means for supporting and positioning may keep the removablecomponent in place in the cavity, such that the removable component doesnot move or relocate within the cavity. Hereby the removable componentis fixedly attached within the model when a dental technician e.g. isusing the model for adjusting dental restorations.

It may be an advantage that the removable component does not have fullcontact with the cavity, but only partly contact in certain few areas orregions. Thus there is a gap between the removable component and thecavity, except at the points where the means for supporting andpositioning are arranged, here there is contact.

In the context of the present disclosure, the phrase “the wall of thecavity” or the equivalent “the cavity wall”, may refer to the part ofthe inner surface of the cavity, which is substantially parallel to thelongitudinal direction of the removable component and/or of the cavityitself. The cavity wall may be the part of the inner surface of thecavity along which the removable component is moved when placing it inor removing it from the cavity.

The cross sectional shape of the cavity may be rounded such that thecavity wall comprises one coherent surface which forms the entire cavitywall.

The cross sectional shape of the cavity may comprise corners eachconnecting two parts of the cavity wall, such as in a cavity comprisingseveral sides which together forms the cavity wall. The cavity may e.g.have a rectangular cross section with four sides which together form thecavity wall.

The contact may be between the surface, e.g. the inner surface, of thecavity and the surface, e.g. the outer or external surface, of theremovable component.

The inner surface may be the wall of the cavity and maybe also thebottom of the cavity.

The physical model can be used as a working model when a dentaltechnician is fitting, testing, adjusting a dental restoration for apatient. A part of the removable component may thus be shaped as atooth, which is prepared for a dental restoration, thus the teethpreparations are originally teeth prepared for a dental restoration,such as a bridge, a crown etc.

In the context of the present disclosure, the phrases “bottom” and “top”may refer to two opposite ends of a part of the model. For instance, aremovable component may comprise a bottom part and a top part, whereinthe phrase “bottom part” may refer to the part of the removablecomponent which is inserted into its corresponding cavity therebydefining an interface between cavity and removable component. The “toppart” of the removable component may be the part which is visible whenthe removable component is inserted into its corresponding cavity. Thephrases “top” or “bottom” are only used to describe the relativeorientation of the parts of the model and does not present a limitationon which part is closer to the ground than the other parts. The openingthough which the removable component enters the cavity may also belocated closer to the ground than the bottom of the cavity or viseversa.

In some embodiments the ratio between the area of contact and the areaof said cavity wall is below about 0.9, such as below about 0.8, such asbelow about 0.7, such as below about 0.6, such as below about 0.5, suchas below about 0.4, such as below about 0.3, such as below about 0.2,such as below about 0.1, such as below about 0.05, such as below about0.02.

In some embodiments the ratio between the area of contact and the areaof said interface is below about 0.9, such as below about 0.8, such asbelow about 0.7, such as below about 0.6, such as below about 0.5, suchas below about 0.4, such as below about 0.3, such as below about 0.2,such as below about 0.1, such as below about 0.05, such as below about0.02.

In some embodiments the area of contact for one supporting element is inthe range of about 0.01 mm² to about 40 mm², such as in the range of 0.1mm² to about 20 mm², such as in the range of 0.5 mm² to about 10 mm².

In some embodiments the width of said supporting element in said area ofcontact is in the range of about 0.01 mm to about 4 mm, such as in therange of about 0.1 mm to about 2 mm.

In some embodiments the length of said supporting element in saidcontact area is in the range of about 0.01 mm to about 20 mm, such as inthe range of about 0.1 mm to about 10 mm.

In some embodiments, the height of the supporting elements is in therange of about 0.05 mm to about 2 mm, such as in the range of about 0.1mm to about 1.5 mm, such as in the range of about 0.2 mm to about 1 mm.

In the context of the present disclosure, the phrase “the width of asupporting element” may refer to the cross sectional dimension of thesupporting element along the interface between the removable componentand the cavity wall.

In the context of the present disclosure, the phrase “the length of asupporting element” may refer to the longitudinal dimension of thesupporting element.

In the context of the present disclosure, the phrase “the height of asupporting element” may refer to the cross sectional dimension of thesupporting element across the gap at the interface between the removablecomponent and the cavity wall, i.e. perpendicular to the surface of theremovable component and/or of the cavity wall.

In some embodiments, the contour of the cavity wall and the contour ofthe removable component are parallel, thus there is a constant distancebetween the contours. In such embodiments there is a constant distancebetween the removable component and the cavity wall except at thesupporting elements, where the supporting elements provide a contactbetween the two.

In the context of the present disclosure, the phrase “the longitudinaldirection” may refer to the insertion direction of the removal componentin the gingival part of the model.

In the context of the present disclosure, the phrase “cross sectional”may refer to a plane which is perpendicular to the longitudinaldirection. The cross sectional shape of e.g. a base of a removableelement may be the shape of the base in such a plane intersecting thebase.

In some embodiments, said means for supporting and positioning aregenerated on said cavity wall. In some embodiments, said means forsupporting and positioning are generated on said removable component. Insome embodiments, means for supporting and positioning are defined onboth the cavity wall and on the removable component.

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth, where the virtual model is based on a virtualrepresentation of the set of teeth, where the virtual model is adaptedto be used for manufacturing a physical model of the set of teeth, wherethe method comprises:

-   -   providing that one or more teeth of the virtual model are        configured to be arranged as one or more removable components in        the physical model,    -   providing means for supporting and positioning each of the        removable components in the physical model.

In some embodiments, a cavity is formed in a gingival part of the model,said cavity comprising a cavity wall, where said means for supportingand positioning are generated on one of the removable component and thecavity wall, such that the means for supporting and positioning extendsacross said gap between said removable component and said cavity wall,where the area of contact between the removable component and the cavitywall at said interface is controlled by the shape of the adjoiningsurfaces of the means for supporting and positioning and the other ofthe removable component and the cavity wall.

In some embodiments, said tooth comprises a tooth which requires arestoration and/or a dental treatment, and for generating a physicalmodel of the set of teeth comprising such a tooth, such that the dentaltechnician can test the dental restorations, e.g. a crown, on thephysical model.

In some embodiments the means for supporting and positioning, such asthe supporting elements, is at least partly shaped so that it resemblesthe shape of the surface of the removable component at the interfaceand/or the shape of the cavity wall.

The shape may be defined as an anatomical shape.

The supporting elements may be shaped so that in the contact area, thesurfaces of the supporting elements and the removable component areparallel. The supporting elements may be shaped so that in the contactarea, the surfaces of the supporting elements and the cavity wall areparallel. The shape of the supporting elements may follow the shape ofthe one of the removable component and the cavity wall on which they aregenerated.

In some embodiments the means for supporting and positioning comprisesone or more friction points providing friction between the removablecomponent and the cavity.

An advantage of this embodiment is that friction points will serve wellas means for supporting and positioning, because they will keep theremovable component in place in the cavity, such that the removablecomponent does not move or relocate within the cavity. Furthermore, thefriction points may be easy to provide virtually and manufacture. Thusthe friction is created due to that the removable component and frictionpoints overlap each other a small distance, e.g. a few millimeters.

In some embodiments, the supporting element comprises one or morefriction points providing friction between the removable component andthe cavity.

The supporting elements are configured such that they cover only afraction of the interface between the removable component and the cavitysuch that the contact area and hence the friction between the removablecomponent and the cavity wall is reduced compared to a physical modelwherein the contact area is substantially identical to the area of theinterface thus resulting in an easier removal of the tooth from thegingival part of a physical model manufactured from the virtual model.

The supporting elements, such as friction points, may provide acontrolled reduction of the friction between the removable component andthe cavity.

In some embodiments the supporting elements are arranged in positionscorresponding to each substantially straight side of the base of theremovable component.

In some embodiments the supporting elements are arranged in positionscorresponding to corners of the base of the removable component.

In some embodiments the supporting elements are arranged such that twosupporting elements are substantially opposing each other.

In some embodiments the supporting elements are arranged such that twosupporting elements are arranged substantially on opposite sides of orrelative to the removable component.

In the context of the present disclosure, the phrase “arranged onopposite sides of or relative to the removable component” may refer tothe case where e.g. first and second supporting elements are arranged onan opposite of the removable component relative to a central part of theremovable component. On a removable component comprising a circularbase, the phrase may refer to the situation where the first and secondsupporting elements are diagonally arranged, such that a line connectingthe first and second supporting elements passes through the center ofthe base. On a removable component comprising a rectangular base, thephrase may refer to the situation, where the first and second supportingelements are arranged on opposing surfaces of the base.

An advantage of this embodiment is that when supporting elements arearranged opposite each other, they may provide a very firm attachment ofthe removable component in the cavity.

In some embodiments the supporting elements are arranged with anequidistant distance to each other.

In some embodiments the distance is measured along the inner surface ofthe cavity or the outer surface of the removable component.

In some embodiments the supporting elements are formed as cut-offpyramids or as square frusta or rectangular frusta.

An advantage of the embodiments is that the friction or the supportingelements are created due to that the removable component and the cut-offpyramids overlap a small distance, e.g. a few millimeters.

In some embodiments, the cut-off pyramids, or the square frusta or therectangular frusta are arranged with the broadest part arranged at thesurface of the cavity and the narrowest part pointing towards theposition, where the removable component is configured to be arranged.

In some embodiments, the cut-off pyramids or square frusta orrectangular frusta are arranged with the broadest part arranged at theone of said removable component and said cavity wall on which they aregenerated, and with the narrowest part at the contact area to the otherof said removable component and said cavity wall.

In some embodiments a number N_(elem) of supporting elements areprovided on the removable component and/or the cavity wall. The numberN_(elem) may be selected from the group of 3, 4, 6, 8, 9, 10, 12 or 16.

In some embodiments the method comprises providing 3 friction points, 4friction points, 6 friction points, 8 friction points, 9 frictionpoints, 10 friction points, 12 friction points, 16 friction points ormore friction points.

In some embodiments, the model comprises a removable component whichcomprises one, two or more teeth.

In some embodiments, the model comprises two or more removablecomponents. Each of the removable components may comprise one or moreteeth

In some embodiments, the contour of the cavity wall follows an outercurve and the contour of the removable component follows an inner curve,where the inner curve is arranged inside the outer curve.

The inner curve and the outer curve may be substantially parallel suchthat said gap has a substantially constant width along the contoursexcept at the positions, where the means for supporting and positioningextend across said gap and close it.

In some embodiments, supporting elements generated on said removablecomponent comprise a surface in the contact area which is substantiallyaligned with the outer curve, such that these supporting elements areshaped to have a surface in the contact area which is parallel to thesurface of the cavity wall at the contact area.

In some embodiments, supporting elements are generated on in the wall ofsaid cavity and comprise a surface in the contact area which issubstantially aligned with the inner curve, such that these supportingelements are shaped to have a surface in the contact area which isparallel to the surface of the removable component at the contact area.

In some embodiments there is a constant distance from the part of thesupporting element pointing towards the position of the removablecomponent to the surface of the cavity.

Alternatively the distance is not constant, e.g. if the shape of themeans for supporting and positioning does not follow the contour of thecavity, but is e.g. a straight line disregarding the anatomical shape.

In some embodiments the method comprises providing four friction points.

In some embodiments the method comprises providing a pin at the base ofeach removable component, where the pin is shaped so that its crosssectional shape resembles the cross sectional shape of the base of theremovable component, where the cross sectional dimension of the pin issmaller than the cross sectional dimension of the base of the removablecomponent

The shape may be defined as an anatomical shape.

An advantage of this embodiment is that when e.g. printing the physicalmodel, there is a need for supporting the large regions of the model,but traditional supports, e.g. being thin or small, can deteriorate thequality of the edge of the removable component resting in the cavity ofthe model. By providing that the geometry of the support pin is adaptedto the shape of the removable component, the traditional or conventionalsupports can be avoided on that edge and thereby the risk of faults isreduced.

The larger the pin is the less may the risk be that it will break.

In some embodiments, the method comprises providing a virtualrepresentation of a set of teeth and forming a virtual model of said setof teeth from said virtual representation.

In some embodiments the virtual representation of the set of teeth isprovided by scanning the set of teeth by means of an intraoral scanneror scanning an impression of the set of teeth. The virtualrepresentation of the set of teeth may comprise a point cloud.

Thus the virtual model and afterwards the physical model may be createdbased on scanning e.g. an impression instead of e.g. creating a model bycasting the model from an impression. An advantage of this embodiment isthat better accuracy is obtained, because the impression itself isscanned instead of scanning a casted or poured model, in which defectsmay have emerged, when making the model. Furthermore, it may be anadvantage that the manual and time consuming work of making the model ingypsum from the impression is avoided. Thus this embodiment provides asimpler and possibly faster and cheaper process.

A reason for manufacturing a physical model from the impression is thatdental technicians may prefer to have a physical model to work with whenthey adapt the dental restoration(s) for a patient.

An advantage of this embodiment is that the impression can be scanned tocreate a representation of both the lower and upper part of the jaws.

An advantage of this embodiment is that the virtual model isautomatically generated in software based on the scanning of theimpression.

In some embodiments the method comprises defining a curve on the virtualmodel and removing everything of the model from visualisation which isoutside this curve.

An advantage of this embodiment is that it enables that only the part ofthe model which the user wishes to work with, and not the entire model,is visualised, e.g. seen or shown on a screen.

In some embodiments the method comprises automatically defining a marginline for a removable component based on the centre of mass of theremovable component.

In some embodiments the method comprises automatically removing neighborteeth in the direction of view such that a user is able to have anunspoiled view of the model for editing a margin line.

In some embodiments the method comprises removing some of the part ofthe model corresponding to the gingiva, such that it becomes easier fora user to take the removable component out of the physical model.

In some embodiments the method comprises defining a cylindercorresponding to an insertion direction such that it can be checked ifthe neighbor teeth are affected when taking the removable component inor out of the model.

In some embodiments the method comprises applying a scan of the entireset of teeth so that the antagonist is visualized, and providing avirtual articulator, so that the entire set of teeth can be occlusiontested.

In some embodiments the method comprises manufacturing the physicalmodel by means of three dimensional printing or milling.

Examples of 3D printing or milling are:

-   -   inkjet-like principle, where it is possible to manufacture the        outer part of the physical model in a high quality and/or an        expensive material, and the inner part can be manufactured in a        cheaper material, such as e.g. wax;    -   standard 3D printing;    -   standard 3D milling;    -   steriolithography (SLA), which is a type of rapid prototyping        process;    -   selective laser sintering (SLS), which is a type of rapid        prototyping process.

In some embodiments the method comprises designing and adapting themodel to be manufactured by means of a specific manufacturing process.

For example different materials can be chosen for manufacturing of thephysical model.

In some embodiments the method comprises designing perforations oropenings in the gingival part of the model pointing away from theremovable components such that fluid used in the manufacturing processis allowed to run out of the model in order to decrease the amount ofmaterial to be used. Thus the model may be hollow and consists of just ashell. An advantage of this embodiment is that if the material shrinksand there is less material, there will be less shrinking and thus lessdefect of the model.

In some embodiments the method comprises defining connectors forconnecting a model of teeth in an upper jaw and a model of teeth in alower jaw such that the two models are adapted to be attached to eachother in an anatomically correct way.

In some embodiments the method comprises that the removable componentand the means for supporting and positioning are manufactured such thatthe removable component is positioned anatomically correct in thephysical model corresponding to the position of the real, anatomicalteeth in the mouth of the patient.

A removable component may also be denoted a tooth, a tooth preparation,a die etc.

In some embodiments the method comprises providing that the shape of thevisible part of the removable component in the model corresponds to thevisible part of the real, anatomical tooth, when the removable componentis arranged in its correct anatomical position in the physical model,whereby no gingiva is part of the removable component.

In some embodiments the correct anatomical position of the removablecomponent is with regard to the height relative to the model, withregard to the horizontal position which can be controlled by ensuringthat the removable component cannot rotate when placed in the modeland/or with regard to the friction between the removable component andthe corresponding cavity in the model.

When the removable component is arranged to have an anatomical correctheight relative to the gingival part of the model, the tooth of theremovable component may be arranged correctly relative to the horizontalplane of the teeth model. When the removable component is arrangedcorrectly with regard to the friction between the removable componentand the cavity, it may be arranged such that the relative position ofthe supporting elements and the removable component/the cavity wall issuch that the supporting elements provide a correct friction.

The physical model of the set of teeth may be used by a dentaltechnician to build up a model of the restoration, which may be known asthe wax modulation. The model of the restoration or the wax modulationmay then be used to cast the actual restoration, which is for examplemade of a metal material, such as a metal crown with porcelainveneering.

The physical model may be used to check whether a manufacturedrestoration actually fits the physical removable component in thephysical model.

Even if the restoration is produced by CAD/CAM, it is still advantageousto check that the produced restoration has a correct fit by checking therestoration on the physical model. There are several steps in themanufacturing process, so potentially something could go wrong in one ofthe steps, and then it is better that the dental technician discoversand corrects a fault before the restoration is send to the dentist andinserted in the patient's mouth.

If the restoration is produced from a material which can change shape orsize, e.g. zirconium dioxide also known as zirconia, it is also anadvantage to check the restoration after production, because thematerial may then shrink or become crooked during and/or after theheating process.

If the restoration is produced manually and/or when the porcelain workon the restoration is performed manually, then the dental technicianneeds a model of the other teeth in the set of teeth to check that thereis space enough between the neighbor teeth for the restoration and thatthe shape of the porcelain match the neighbor teeth.

If the model is manufactured by 3D printing, many models can bemanufactured simultaneously compared to fx manufacturing by milling.

The method may comprise that at least one tooth is not removablyinserted in the physical model i.e. the tooth can not be removed fromthe model but is manufactured as part of the model, and is thereforefixed in the model.

The method may comprise that at least one tooth is manufactured as fixedpart of a coherent structure comprising the gingival part and the fixedtooth, such that the fixed tooth can not be removed from the gingivalpart.

This may be an advantage when fabricating veneers in a lab, since herebyit may not be necessary to remove the tooth from the model. Furthermore,it may be an advantage to control the restoration in a completelyinflexible model with no removable component, since this may provide avery good control.

In some embodiments the method comprises that the removable componentsare manufactured to have no pins.

It may be an advantage that by manufacturing the physical model withcavities for the removable components, pins may be omitted from theremovable components, and this may be an advantage since pins may belikely to brake of from the removable components, and pins may hinder orobstruct a perfect fit of the removable components in the model, etc.

Furthermore, if manufacturing a removable component and the model bysolidifying a liquid layerwise, it may be difficult to produce a pin,since the stop surface on the rest of the removable component is notcarried or supported by anything as it is being produced in the liquid.

In some embodiments the method comprises digitally repositioning thegingival part of the model around the removable component, beforemanufacturing the model.

This repositioning may be an advantage because often it is a problemthat when a tooth is prepared in the mouth of the patient, then so muchof the tooth is grinded away, whereby the soft, compliant gingivaltissue around the prepared tooth will adjoin or follow or collapse tothe new reduced shape of the prepared tooth instead of remaining in theoriginal shape following the non-prepared tooth. So when e.g. theimpression of the prepared tooth is made, then the gingiva is adjoiningthe prepared tooth and the manufactured model of the teeth will thenhave a gingiva adjoining the removable component, and thus there may beno space between the gingival and the removable component to model andplace a restoration. But when repositioning, removing, or relocating thegingival part of the model around the removable component then there isspace for the restoration and the veneering, e.g. porcelain, which thedentist may add after having inserted the restoration in the mouth ofthe patient.

In some embodiments, digitally repositioning the gingival part of themodel comprises digitally moving the gingival part of the model awayfrom to the removable component.

The digital repositioning the gingival part of the model may comprisemoving the gingiva adjoining the removable component.

In some embodiments digitally repositioning the gingival part of themodel comprises digitally moving the gingival part of the model outwardsrelative to the removable component.

It may be an advantage that the gingival part of the model may be movedwithout changing the size of gingiva, which is important since thegingival in the mouth of the patient also will only change shape andmove but not change size, i.e. the gingival does not become bigger orsmaller, it only changes shape.

It may be an advantage that if the model of the restoration is designedusing CAD, then it can be derived from the CAD program how much thegingiva on the teeth model should be moved in order to fit the modeledrestoration.

In some embodiments the method comprises that the teeth of the model ismanufactured in a hard, non-flexible material and at least the gingivalof the model around the removable component is manufactured in a soft,flexible material.

In some embodiments the method comprises that the teeth of the model aremanufactured in a relatively harder, less flexible material and at leastthe gingival of the model around the removable component is manufacturedin a relatively softer, more flexible material.

It may be an advantage to manufacture the teeth of the model in arelatively harder material and the gingival part of the model in arelatively softer material, because then the different materialsresemble the real materials in the mouth, and this facilitates thetesting or modeling of the restoration.

In some embodiments the shape of the supporting elements in a planedefined by the interface are bars, squares, ovals, stars, or triangles.

In some embodiments the method comprises that the volume of a supportingelement generated on the cavity wall is manufactured to overlap at leastpartly with the volume of the removable component, when the removablecomponent is arranged in the cavity, such that a tight fit is createdbetween the cavity and the removable component.

In some embodiments, the volume of a supporting element generated on aremovable component is manufactured to overlap at least partly with thevolume of the cavity wall, such that when the removable component isarranged in the cavity a tight fit is created between the cavity and theremovable component.

In some embodiments, the volume of a supporting element of a removablecomponent is manufactured to overlap at least partly with the volume ofthe other of the removable component and the cavity wall, such that atight fit is created between the cavity and the removable component.

In some embodiments the volume of the overlap is adapted to becontrolled by an operator.

In some embodiments the method comprises providing that the modelcomprises a side ejection hole through which the removable component inthe physical model can be contacted and ejected from its cavity.

The hole may be arranged in the gingival part of the model.

It may be an advantage that when providing an ejection hole in the sideon the model, then this hole is accessible from the side, which may bean advantage when e.g. mounting the model on an articulator, where theside of the model can be accessed as opposed to the bottom of the modelwhich is attached to the articulator. Therefore it may be an advantageto arrange the ejection hole on the side of the model instead of in thebottom of the model. However, a hole, e.g. an ejection hole, mayalternatively and/or additionally be arranged in the bottom of themodel.

In some embodiments, the method comprises providing that the removablecomponent comprises a hole adapted to be arranged in continuation of theside ejection hole in the model, when the removable component isarranged in the cavity of the model.

It may be an advantage that when providing a hole in the side of themodel and a hole in the removable component, then when the two holes arealigned, i.e. arranged in continuation of each other, or arranged end toend, then the removable component is arranged correctly relative to themodel.

Whether the hole in the removable component and the hole the in modelare aligned can be checked by means of visual inspection or by using atool adapted to fit into the holes. Thus when the tool can movetrouble-free through the hole in the model and into the hole in theremovable component, then the alignment of the removable component inthe model will be correct. In some embodiments the side ejections holeis arranged such that the tool can move the entire way through both themodel and the removable component, thus the tool is inserted on one sideof the model and can pass through the model to the other side of themodel. Thus in some embodiments, the side ejection hole is arranged suchthat a tool can pass through a section of the model comprising both theremovable component and the gingival part of the model surrounding thecavity in which the removable component is arranged, such that the toolcan be inserted on one side of the section and can pass through thesection to a side of the section arranged opposite to the removablecomponent.

In some embodiments the method comprises arranging the hole in the modelas a through hole passing from the surface of model to the cavity forthe removable component, and arranging the hole in the removablecomponent as a blind hole.

The through hole may be passing from the gingival part of the model. Thehole in the removable component may be arranged as a blind hole in aposition corresponding to the root of the tooth.

In some embodiments the method comprises arranging the hole in the modelas a through hole passing from the surface of model to the cavity forthe removable component, and arranging the hole in the removablecomponent as a through hole.

The through hole may be passing from the gingival part of the model. Thehole in the removable component may be arranged as a through hole in aposition corresponding to the root of the tooth.

Thus the hole in the removable component may be a through hole passingthe entire way through the removable component to the other side of thecavity. In this case the hole in the model may then pass through theentire model, i.e. passing from the surface of the model to one end ofthe cavity inside the model, and from the other end of the cavitythrough the model to the other surface of the model.

It may be an advantage to have a side ejection hole which is a throughhole in both the model and the removable component, since then thepositioning of the removable component in the model can be checked byvisual inspection, which may be facilitated when there is a free passagethrough the entire model and removable component.

Furthermore, it may be an advantage for the manufacturing of the modeland the removable component to produce the side ejection holes a throughholes. For example, the model and removable component can bemanufactured by means of jet printing, and for example a soft supportmaterial may be arranged in the model and the removable component atplaces where there should be no material in the final version. When themanufacturing of the model or the removable component has beencompleted, the support material will be removed, e.g. washed away,melted away or digged away. In this case it may be easier to remove allthe support material from a hole if the hole is a through hole insteadof a blind hole.

In some embodiments the method comprises arranging the removablecomponent in the gingival part of the model such that the removablecomponent is adapted to be inserted in and removed from the gingivalpart of the model without conflicting with or being blocked by theneighbor teeth in the model.

In some embodiments the method comprises arranging the removablecomponent in the model such that the insertion direction of theremovable component corresponds to the insertion direction of the real,anatomical tooth in the set of teeth.

In some embodiments the method comprises arranging the removablecomponent in the gingival part of the model such that the insertiondirection of the removable component is so skew that the removablecomponent is adapted to be inserted in and removed from the gingivalpart of the model without conflicting or being blocked by the neighborteeth in the model.

In some embodiments the method comprises providing that the modelcomprises a stop surface functioning as a stop for the removablecomponent when arranged in the cavity, such that the removable componentis hindered from being pushed further into the gingival part of themodel than the correct anatomical height of the removable componentcorresponds to.

In some embodiments the stop surface is plane and horizontal.

The stop surface may be plane and horizontal relative to the rest of themodel, and/or relative to the insertion direction of the removablecomponent etc.

It may be an advantage that the stop surface is plane and horizontalsince this may provide an optimal positioning and support of theremovable component in the model.

In the context of the present invention, the phrase “horizontal” mayrefer to a plane which is substantially parallel to the occlusion planeof the patient's dentition.

In some embodiments the method comprises that when the model is 3Dprinted, at least part of the stop surface is horizontal with respect tothe remainder of the model.

Thus the overall form of the stop surface may be sloping, slanting orinclined, but each single printing layer should be horizontal so thesloping surface will be made up of several small horizontal parts. Thisprovides a very good set fit.

If the model is milled instead of 3D printed, then the stop surface maynot be horizontal, but can be in any direction.

In some embodiments the method comprises that the stop surface isarranged in a printing layer which is also present in the remainder ofthe model.

It may be an advantage because the stop surface is then level with thebottom part of the removable component, whereby the removable componentcan be pushed down exactly to the right layer in the model, whereby theposition of the removable component in the model is anatomically correctwith respect to the height of the removable component in the physicalmodel.

Thus the stop layer is at a height h which is h=n×printing layerthickness.

In some embodiments the method comprises providing that the removablecomponent has a top part, which is visible, when the removable componentis arranged in its corresponding cavity in the model, and a bottom part,which is hidden by the gingival part of the model and therefore notinvisible, when the removable component is arranged in its correspondingcavity in the model.

In some embodiments the method comprises providing that at least thebottom part of the removable component is substantially cylindrical.

In some embodiments the method comprises providing that at least thebottom part of the removable component is substantially rectangular.

An advantage of this embodiment is that when the bottom part of theremovable component is rectangular, the removable component cannotrotate in the cavity, and its positioning in the model is therefore wellfixed.

In some embodiments the method comprises that the cross section area ofthe removable component is constant along the part of the removablecomponent, which is adapted to be covered by the gingival part of themodel, when the removable component is inserted in its cavity.

In some embodiments the method comprises that the cross section area ofthe removable component is constant along the part of the removablecomponent, which is arranged at said interface, when the removablecomponent is inserted in its cavity. An advantage of this is that whenthe removable component has a constant thickness in the model, then theremovable component may have a stable fit, for example without using anypins.

The part of the removable component which is covered by the gingivalpart of the model is not visible, when the removable component isarranged in the model, and when the model is made in a non-transparentmaterial. However, if the model is made in a transparent material, thenthe part of the removable component which is in the cavity of the model,may still be visible.

In some embodiments the method comprises that the shape of the crosssection is constant along the part of the removable component, which isadapted to be covered by the gingival part of the model, when theremovable component is inserted in its cavity.

In some embodiments, the method comprises that the shape of the crosssection is constant along the part of the removable component, which isarranged at said interface, when the removable component is inserted inits cavity.

In some embodiments the method comprises providing that one or moreadjacent teeth of the removable component in the model are adapted to beremovably inserted in the model.

An advantage is that when the adjacent or neighbor teeth can be removedfrom the model, then it may be easier for the dental technician to buildup the model of a restoration, since then there is free space around theremovable component, e.g. on all or some of the sides.

In some embodiments the method comprises providing that the removablecomponent comprises an anatomical layer, a margin line layer, aconnection layer and a base layer.

In some embodiments the removable component comprises a ditch layerarranged between the margin line layer and the connection layer forproviding workspace.

An advantage of this embodiment is that the ditch layer provides workingspace on the removable component for the dental technician, such thatthe dental technician have space enough to work with for example adental drill etc.

In some embodiments the removable component comprises a pin.

An advantage of this embodiment is that a pin may provide a better fitof the removable component in the model.

In some embodiments the method comprises providing an identification tagon at least one removable component.

In some embodiments the method comprises providing an identification tagon each removable component. This identification tag may be providedwhen manufacturing the removable component and the model.

It may be an advantage because when providing an identification (ID) tagthen it is easy to identify the removable components, when for example alarge batch of removable components are manufactured together. The IDtag may be printed a suitable place in the removable component, may beattached to the model and may be detachable etc.

The identification tag may be provided on the virtual model and/or thephysical model.

In some embodiments the method comprises providing a identificationnumber on each removable component and providing the correspondingidentification number at the corresponding cavity in the model for eachremovable component.

It may be an advantage because if there are several removable componentsin a model, then it may be complicated to find out or see where eachremovable component should be arranged in the model. When providing theidentification numbers then it is easy and fast to arrange the removablecomponents in their correct cavities in the model.

In some embodiments the method comprises providing visual guidelines onthe removable component and the gingival part of the model for arrangingthe removable component correct relative to the gingival part of themodel.

The visual guidelines may be printed, embossed etc., and may be groovesor elevations.

In some embodiments the method comprises manufacturing the model to behollow.

It may be an advantage because then less material is used, and thesmaller amount of material that is used, the smaller will the degree ofdistortion of the model be after manufacturing There may also be aneconomic advantage of providing a hollow model, because using lessmaterial makes the manufacturing process less costly and possibly alsofaster.

In some embodiments the method comprises providing the model withconnector pins. The connector pins may be configured such that theyconnect the model to e.g. an articulator.

It may be an advantage because if both a model of the upper jaw and amodel of the lower jaw are manufactured, then the two models can beconnected by the connector pins such that the occlusion of the patientcan be tested, e.g. by arranging the upper and the lower model in anarticulator.

In some embodiments the method comprises providing the model with aninterface adapted for matching a specific articulator in which theocclusion of the patient is tested.

In some embodiments the method comprises manufacturing an articulatorplate matching the interface of the model.

The present disclosure relates to different aspects including the methoddescribed above and in the following, and corresponding methods,devices, systems, uses and/or product means, each yielding one or moreof the benefits and advantages described in connection with the firstmentioned aspect, and each having one or more embodiments correspondingto the embodiments described in connection with the first mentionedaspect and/or disclosed in the appended claims.

In particular, it is disclosed herein is a computer-implemented methodof generating a virtual model of a set of teeth for manufacturing aphysical model of the set of teeth, where the model comprises one ormore teeth preparations, where the method comprises:

-   -   generating a virtual model of the set of teeth, where the        virtual model is based on a virtual representation of the set of        teeth;    -   providing that each of the teeth preparations is configured to        be arranged as part of a removable component in the model, where        each removable component is adapted to fit into a corresponding        cavity in the gingival part of the model;    -   providing means for supporting and positioning each of the        removable components in their corresponding cavity in the model.    -   providing a pin at the base of each removable component, where        the pin is shaped so that it resembles the shape of the        removable component.

In particular, disclosed herein is a computer-implemented method ofgenerating a virtual model of a set of teeth for manufacturing aphysical model of the set of teeth, where the method comprises:

-   -   generating a virtual model of the set of teeth, where the        virtual model is based on a virtual representation of the set of        teeth;    -   providing that at least one tooth is configured to be arranged        as part of a removable component in the model, where the        removable component is adapted to fit into a corresponding        cavity in the gingival part of the model;    -   providing means for supporting and positioning each of the        removable components in its corresponding cavity in the model.    -   providing a pin at the base of the removable component.

The cross sectional shape of the pin may resemble the cross sectionalshape of the base of the removable component.

In particular, disclosed herein is a system for generating a virtualmodel of a set of teeth for manufacturing a physical model of the set ofteeth, where the model comprises one or more teeth preparations, wherethe system comprises:

-   -   means for generating a virtual model of the set of teeth, where        the virtual model is based on a virtual representation of the        set of teeth;    -   means for providing that each of the teeth preparations is        configured to be arranged as a removable component in the model,        where each removable component is adapted to fit into a        corresponding cavity in the gingival part of the model;    -   means for providing means for supporting and positioning each of        the removable components in their corresponding cavities in the        model.

The system further comprises:

-   -   means for configuring the means for supporting and positioning        such that the area of contact between each removable component        and its corresponding cavity is smaller than the area in which        there is no contact between the removable component and the        cavity.

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth for manufacturing a physical model of the set ofteeth, the method comprising:

-   -   providing a virtual representation of a set of teeth;    -   generating a virtual model of the set of teeth from said virtual        representation, said virtual model comprising a gingival part        and at least one tooth, said generating comprising:    -   a: configuring said tooth to be part of a removable component in        the model;    -   b: defining a cavity in said gingival part, said cavity        comprising a cavity wall; and    -   c: defining means for supporting and positioning capable of        supporting and positioning the removable component in the cavity        in a physical model manufactured from the virtual model;        wherein the removable component and the cavity are configured so        that the removable component fits into the cavity such that an        interface between the removable component and the cavity wall is        defined and such that the removable component and the cavity        provide a gap at said interface;        wherein the means for supporting and positioning are generated        on one of said removable component and said cavity wall such        that the means for supporting and positioning extends across        said gap between said removable component and said cavity wall;        and        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the other of the removable component or the        cavity wall.

In some embodiments, a) is performed before b), such that the methodcomprises configuring said tooth to be part of a removable component inthe model before the cavity.

In some embodiments, b) is performed before a), such that the methodcomprises defining said cavity before the said tooth is configured to bepart of a removable component in the model.

In some embodiments, said means for supporting and positioning, saidremovable component and the corresponding cavity are formed in one step.

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth for manufacturing a physical model of the set ofteeth, the method comprising:

-   -   providing a virtual model of the set of teeth, the model        comprising a gingival part and a tooth configured to be part of        a removable component in the model;    -   generating a cavity in said gingival part, said cavity        comprising a cavity wall, into which cavity said removable        component fits such that an interface between the removable        component and the cavity wall is defined, where the removable        component and the cavity are configured to provide a gap at said        interface; and    -   providing means for supporting and positioning on the removable        component and/or on the cavity wall such that in a physical        model manufactured from the virtual model, the means for        supporting and positioning extends across said gap between said        removable component and said cavity wall such that the means for        supporting and positioning support and position the removable        component in the cavity;        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the cavity wall and/or the removable component.

Disclosed is a computer-implemented method of generating a virtual modelof a set of teeth for manufacturing a physical model of the set ofteeth, where the method comprises:

-   -   providing a virtual model of the set of teeth;    -   providing that at least one tooth is configured to be arranged        as a part of removable component in the model, where the        removable component is adapted to fit into a corresponding        cavity in the gingival part of the model such that an interface        between the removable component and a cavity wall is defined;    -   providing means for supporting and positioning the removable        components in the cavity in the model; and    -   configuring the means for supporting and positioning such that        the area of contact between the removable component and the        cavity wall is smaller than the area of said interface.

Disclosed is a computer-implemented method of controlling the area ofcontact between a gingival part of a model of a set of teeth and aremovable component in the model, said removable component comprising atooth, wherein the method comprises:

-   -   providing a virtual model of the set of teeth, the model        comprising a gingival part and a tooth configured to be part of        a removable component in the model, where said gingival part        comprises a cavity comprising a cavity wall, into which cavity        said removable component fits such that an interface between the        removable component and the cavity wall is defined, where the        removable component and the cavity are configured to provide a        gap at said interface; and    -   providing means for supporting and positioning on one of said        removable component and said cavity wall such that in a physical        model manufactured from the virtual model, the means for        supporting and positioning extends across said gap between said        removable component and said cavity wall such that the means for        supporting and positioning support and position the removable        component in the cavity;        wherein the area of contact between the removable component and        the cavity wall at said interface is controlled by the shape of        the adjoining surfaces of the means for supporting and        positioning and the other of the removable component and the        cavity wall.

Disclosed is also a computer program product comprising program codemeans for causing a data processing system to perform the method, whensaid program code means are executed on the data processing system, anda computer program product comprising a computer-readable medium havingstored there on the program code means.

According to another aspect, disclosed is also an ejection tool forejecting a removable component arranged in a physical model of a set ofteeth.

In some embodiments the ejection tool comprises an elongated componentwhich is adapted to fit into a through hole in the gingival part of themodel.

In some embodiments the ejection tool is adapted to fit into a blindhole and/or a through hole in the removable component.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or additional objects, features and advantages of thepresent disclosure, will be further elucidated by the followingillustrative and non-limiting detailed description of embodiments of thepresent invention, with reference to the appended drawings, wherein:

FIG. 1 shows an example of a flow chart of the method.

FIG. 2 shows an example of a virtual model of a set of teeth seen fromthe side.

FIG. 3 shows an example of a virtual model of a set of teeth seen fromabove.

FIG. 4 shows an example where a tooth is a removable component in themodel.

FIG. 5 shows in a perspective view examples of supporting elements

FIG. 6 shows an example of an intersection plane of the model.

FIG. 7 shows an example of a removable component with a pin having ashape corresponding to the shape of the base of the removable component.

FIG. 8 shows an example of a side view of a removable component in amodel with a side ejection hole and a bottom ejection hole.

FIG. 9-11 shows an example of a removable component and model with aside ejection hole.

FIG. 12 shows an example of a removable component with a pin in a model.

FIG. 13 shows an example of a removable component.

FIG. 14 shows an example of a cavity of a model and a removablecomponent with non-straight sides.

FIG. 15 shows an example of a cavity of a model and a removablecomponent with non-straight sides.

FIG. 16 shows an example of removable components with indentations.

FIG. 17 shows an example of moving the gingival part of the model aroundthe removable component.

FIG. 18 shows an example of visual guidelines on the removable componentand gingival part of the model.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, reference is made to the accompanyingfigures, which show by way of illustration how the invention may bepracticed.

FIG. 1 shows an example of a flow chart of one embodiment of the method.

In step 101 a virtual model of a set of teeth is generated, and thevirtual model is based on a virtual representation of the set of teeth.The virtual representation may be provided by scanning an impression ofthe set of teeth or scanning the set of teeth directly in the mouth ofthe patient using an intraoral scanner. The virtual model may compriseone or more teeth. The virtual model may have been generated previouslyand the invention is not limited to methods including the generation ofthe virtual model.

In step 102 each of the teeth are provided to be configured to bearranged as a removable component in the model, and each removablecomponent is adapted to fit into a corresponding cavity in the gingivalpart of the model.

In step 103 means for supporting and positioning each of the removablecomponents in their corresponding cavities in the model are provided.

In step 104 the means for supporting and positioning are configured suchthat the area of contact at the interface between the removablecomponent and the cavity wall is controlled by the shape of theadjoining surfaces of the means for supporting and positioning and theremovable component or the cavity wall.

The invention is not limited to a method and systems wherein these stepsare performed in the abovementioned order. For instance, step 103 may beperformed before step 102, or the steps may be performed simultaneously.

FIG. 2 shows an example of a virtual model of a set of teeth seen fromthe side.

The virtual model 201 shows a number of teeth 202 in both the upper 203and lower 204 jaw. A tooth preparation 205 is shown in the upper jaw203.

The virtual model 201 is hollow, thus only forming a shell indicatingthe surface contour of the teeth. The virtual model 201 may be providedby e.g. scanning an impression.

FIG. 3 shows an example of a virtual model of a set of teeth seen fromabove. The virtual model 301 shows a number of teeth 302 and a toothpreparation 305 seen from above. The cusps 306 of the teeth 302 can beseen, whereas there are no cusps on the prepared tooth 305, because thecusps here has been removed when preparing the teeth for a dentalrestoration, such as e.g. a crown or a bridge.

FIG. 4 shows an example where a tooth preparation is a removablecomponent in the model.

In FIG. 4a ) a model 401 of a set of teeth is shown, and the set ofteeth comprises a couple of teeth 402 and a tooth preparation 405. Thetooth preparation 405 is arranged as a removable component in itscorresponding cavity 407 in the model 401.

Some of the part of the model 401 corresponding to the gingiva may havebeen removed, such that it is easier for a user to take the removablecomponent 405 out of the model 401.

The margin line 410 for the removable component 405 may have beenautomatically defined based on the centre of mass of the removablecomponent 405.

In FIG. 4b ) a tooth preparation 405 is shown as a removable componentlifted up from the cavity 407 and thus the removable component isarranged outside its corresponding cavity 407 in the model 401.

Supporting elements 409 supporting and positioning the removablecomponent 405 in the cavity 407 is seen, when the removable component405 is lifted away from the cavity 407. In this example the supportingelements are shown as friction points with a shape of cut-off pyramidsor rectangular frusta.

In both FIG. 4a ) and FIG. 4b ) connector pins 408 are seen on the model401. By means of connector pins 408 a lower jaw and an upper jaw modelof a set of teeth can be connected together in an anatomically correctway.

FIG. 5 shows in a perspective view examples of supporting elements.

FIGS. 5a ), 5 b) and 5 c) all show a cavity 507 with supporting elements509 in the form of friction points shaped as cut-off pyramids orrectangular frusta. The cut-off pyramids or rectangular frusta arearranged with the broadest part arranged at the surface of the cavityand the narrowest part pointing towards the position, where theremovable component is configured to be arranged.

In FIG. 5a ) two friction points 509 are seen, in FIG. 5b ) fourfriction points are seen, and in FIG. 5c ) three friction points areseen.

The friction points are shaped so that they follow the surfaces of theremovable component and of the cavity 507 at the interface, and there isa constant distance from the part of the friction point pointing towardsthe position of the removable component to the surface of the cavity,i.e. the friction points have a constant height.

In FIG. 5b ) four friction points are arranged in positionscorresponding to the four corners of the removable component and of thecavity.

The friction points are arranged such that the friction points aresubstantially opposing each other two and two or in pairs.

Some of the part of the model 501 corresponding to the gingiva may havebeen removed, such that it is easier for a user to take the removablecomponent out of the model 501.

FIG. 6 shows an example of an intersection plane of the model.

FIG. 6a ) shows the model 601 with an intersection plane 611. The model601 comprises the removable component 605.

FIG. 6b ) shows the cross section of the removable component 605 and thecavity 607 at the intersection plane seen in FIG. 6a ).

Supporting elements 609 are shown as friction points in the crosssection view in FIG. 6b ). The contour of the cavity 607 and the contourof the removable component 605 are parallel, thus there is a constantdistance between the contours, except at the friction points 609, wherethe distance is another constant distance.

In FIG. 6b ) of the cross section is seen that at the supportingelements 609, the contour of the supporting elements 609 or frictionpoints in the cavity overlap the contour of the removable component 605a little bit, and this will provide that the removable component 605 isfirmly arranged in the cavity 607. Thus the friction is created due tothat the removable component and the cut-off pyramids overlap a smalldistance, e.g. a few millimeters. The overlap may be one tenth, onehundredth or the like of a millimeter.

FIG. 7 shows an example of a removable component with a pin having ashape corresponding to the shape of the base of the removable component,i.e. the pin is shaped so that its cross sectional shape resembles thecross sectional shape of the base of the removable component.

The removable component 705 comprises a pin 712 which has a shaperesembling the shape or contour of the removable component 705. The pinmay be wider or narrower, longer or shorter than shown in this example.A large pin may provide good support for the removable component 705 ina physical model of a set of teeth.

FIG. 8 shows an example of a side view of a removable component in amodel with a side ejection hole and a bottom ejection hole.

FIG. 8a ) shows a removable component 805 arranged in a gingival part ofthe model 801. The model 801 with the removable component 805 comprisesa side ejection hole 813. The side ejection hole 813 is a through holein the side of the model 801, and a blind hole in the side of theremovable component 805. The model 801 also comprises a bottom ejectionhole 814, which is a through hole in the bottom of the model 801. Whenthe removable component 805 is arranged in the model 801 it rests on thestop surface 815 of the model 801, and the bottom of the removablecomponent 805 forms the end of or closes the bottom ejection hole 814.The stop surface may be plane and horizontal for providing an optimalpositioning and support of the removable component in the model.

The side election hole 813 and the bottom ejection hole can be used forejecting the removable component 805 from the gingival part of the model801.

The removable component comprises an anatomical part 816, which is thetop of the removable component, and a bottom, standard part 818 which isthe part arranged in the cavity 807 of the model 801, and a connectionarea 817, which is the part between the anatomical part 816 and thebottom standard part 818.

Alternatively and/or additionally, the bottom standard part 818 is notarranged in a cavity 807 of the model 801, but may be arranged on amodel 801 having no cavities.

FIG. 8b ) shows an example of a top view of a removable component 805.

The line 816 shows the anatomical part 816 of the removable component,and the line 818 shows the bottom, standard part 818 of the removablecomponent, as seen in FIG. 8a ). The cut-off triangles or crushingpyramids show the friction points 809 on the model 801. The frictionpoints 809, in e.g. the cavity of the model 801, have the function tofacilitate support and positioning of the removable component 805 in themodel 801.

FIG. 9 shows an example of a removable component and model with a sideejection hole which is a through hole.

FIG. 9a ) shows a side view of a part of a model 901 with a sideejection hole 913 being a through hole. The side ejection hole 913 is athrough hole from the outside surface of the model 901 to the cavitypart 907 of the model and again from the other end of the cavity part907 to the other surface of the model 901.

FIG. 9b ) shows a side view of a removable component 905 fitting intothe cavity 907 of the model 901. The side ejection hole 913 is a throughhole in the bottom part of the removable component 905. FIG. 9c ) showsa side view of the removable component 905, where the removablecomponent has been rotated 90 degrees relative to the view in FIG. 9b ),so that the side ejection hole 913 is seen from the front.

FIG. 9d ) shows a side view of the model 901 with the removablecomponent 905, where the removable component 905 is arranged in thecavity 907 of the model 901. It is seen that the side ejection hole 913in the removable component 905 and in the model 901 are arranged exactlyon line such that the part of the side ejection hole 913 in theremovable component 905 and the part of the side ejection hole in themodel 901 are arranged exactly end to end.

FIG. 10 shows an example of a model with a removable component with aside ejection hole 1013, where the hole in the removable component 1005is a through hole passing along the entire width of the removablecomponent 1005. The side ejection hole 1013 only passes through one sideof the model 1001, but not through the other side of the model.

The cavity 1007 of the model 1001, see FIG. 10a ), and the bottom,standard part 1018 of the removable component 1005, see FIG. 10b ), havestraight sides that are arranged with a slope. Thus the sides do notform straight angles.

FIG. 10c ) shows the model 1001 with the removable component 1005.

FIG. 11 shows an example of a model with a removable component with aside ejection hole 1113, where the hole in the removable component 1105is a blind hole.

FIG. 11 shows that the side ejection hole 1113 of the model 1101 isstraight, but that the blind hole 1113 of the removable component 1105has a sloping side.

Furthermore, the model 1101 comprises a bottom ejection hole 1114.

FIG. 12 shows an example of a removable component with a pin in a model.The figure shows that the removable component 1205 is arranged in amodel 1201. The model 1201 does not comprise a cavity, so the removablecomponent 1205 is just arranged next to the adjacent or neighbour teeth1219 in the free space in the model 1201. The removable component 1205comprises a thin, elongated pin 1212 which fits into a hole 1220 in themodel 1201, see also the blow up showing an enlargement of the pin 1212and the hole 1220.

The margin line 1210 of the removable component 1205 is also marked.

FIG. 13 shows an example of a removable component.

The removable component 1305 comprises an anatomical layer 1316, amargin line layer 1310, a ditch layer 1321, a connection layer 1317 anda base or bottom layer 1318.

The ditch layer 1321 is optional, but the advantage of providing a ditchlayer 1321 between the margin line layer 1310 and the connection layer1317 is for providing workspace for the dental technician on theremovable component 1305.

Furthermore, a pin 1312 may be arranged under the base layer 1318.

FIG. 14 shows an example of a cavity of a model and a removablecomponent with non-straight sides.

FIG. 14a ) shows that the cavity 1407 of the model 1401 is formed asstairs 1422, and FIG. 14b ) shows that the bottom part of the removablecomponent 1405 is formed as corresponding stairs 1422. The stairs areoverall non-straight, but the single steps of the stairs may bestraight. The size of the stairs may be much smaller than shown here,they may be so small that they can no be seen with the naked eye. Ifthere are many stairs, then the overall visual impression will be thatthe side is actually sloping.

It is optional whether the bottom of the cavity is closed or open, whichis indicated with a broken line.

FIG. 15 shows an example of a cavity of a model and a removablecomponent with non-straight sides.

FIG. 15a ) shows that the cavity 1507 of the model 1501 is formed asstairs 1522, and FIG. 15b ) shows that the bottom part of the removablecomponent 1505 is formed as corresponding stairs 1522. The stairs areoverall non-straight, but the single steps of the stairs may bestraight.

The removable component 1505 comprises a pin 1512, which is shown to beso long that it extends all the way through the model 1501. It isoptional whether the bottom of the hole in the model 1501 for the pin1512 is closed or open, which is indicated with a broken line.

FIG. 16 shows an example of removable components with indentations.

FIG. 16a )-b) shows that instead of e.g. cavities in the model, theremovable component 1605 can have indentations 1623 which facilitatesthe support and positioning of the removable component 1605 in themodel, where the model may be in the form of a mounting base 1630. Themounting base 1630 may be a standard or generic mounting base or aspecific mounting base for the specific patient case.

FIG. 16a ) furthermore shows that the mounting base 1630 can haveprotrusions 1624 which fits into the indentations 1623 of the removablecomponent 1605.

FIG. 17 shows an example of moving the gingiva around the removablecomponent.

FIG. 17a ) shows the model 1701 before a portion of the gingiva 1725 ofthe model has been repositioned.

FIG. 17b ) shows the model 1701 after a portion of the gingiva 1725 ofthe model has been repositioned. After the gingiva part 1725 has beenmoved, the model 1701 can be manufactured.

When a tooth is prepared in the mouth of the patient, so much of thetooth may be grinded away, that the soft, compliant gingival tissuearound the prepared tooth will adjoin or follow or collapse to followthe new reduced shape of the prepared tooth instead of remaining in theoriginal shape following the original non-prepared tooth. When digitallyrepositioning, removing, or relocating the gingival part 1725 of themodel 1701 around the removable component 1705 then there is space for arestoration 1726 and veneering.

The gingival part 1725 of the model 1701 is moved outwards relative tothe removable component 1705, i.e. away from the removable component,and it is moved without changing the size of gingival part 1725, onlythe shape of the gingival part 1725 is changed.

If the restoration 1726 is designed using CAD, it can be derived fromthe CAD program how much the gingival part 1725 on the model 1701 shouldbe moved in order to fit the modeled restoration 1726.

In FIG. 17, the removable component 1705 is not shown as a removablecomponent but as a fixed part of the model 1701 and thus the component1705 could be denoted a tooth or die in this case.

FIG. 18 shows an example of visual guidelines on the removable componentand mounting base.

Visual guidelines 1828 may be provided for facilitating a correctarrangement of the removable component 1805 relative to the model ormounting base 1830. A mounting base 1830 is shown here, because theremovable component 1805 is shown to be a stand-alone component and nota component to be arranged in a cavity of a model, however, visualguidelines may of course also be arranged on a model with cavities forthe removable component. The mounting base 1830 may be a standard orgeneric mounting base or a specific mounting base for the specificpatient case.

The visual guidelines 1828 are straight lines which are present on boththe removable components 1805 and on the mounting base 1830. When theremovable component 1805 is arranged correctly relative to the mountingbase 1830, then the visual guidelines 1828 on the removable component1805 and the mounting base 1830 match, meet, or fit together.

The visual guidelines 1828 may be printed, embossed etc., and may e.g.be grooves or elevations.

Furthermore, corresponding numbers 1829, here number 6, are arranged onthe removable component 1805 and on the mounting base 1830 for keepingtrack of where the different removable components 1805 should bearranged in the mounting base 1830, when there are more removablecomponents 1805 which could be difficult to distinguish from each other.

Although some embodiments have been described and shown in detail, theinvention is not restricted to them, but may also be embodied in otherways within the scope of the subject matter defined in the followingclaims. In particular, it is to be understood that other embodiments maybe utilised and structural and functional modifications may be madewithout departing from the scope of the present invention.

In device claims enumerating several means, several of these means canbe embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims ordescribed in different embodiments does not indicate that a combinationof these measures cannot be used to advantage.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

It should be emphasized that the term “according to any of the precedingclaims” may be interpreted as meaning “according to any one or more ofthe preceding claims”, such that the limitations of one or severaldependent claims may be read into an independent claim.

The features of the method described above and in the following may beimplemented in software and carried out on a data processing system orother processing means caused by the execution of computer-executableinstructions. The instructions may be program code means loaded in amemory, such as a RAM, from a storage medium or from another computervia a computer network. Alternatively, the described features may beimplemented by hardwired circuitry instead of software or in combinationwith software.

The invention claimed is:
 1. A method of generating a virtual model of aset of teeth for manufacturing a physical model of the set of teeth,where the generated virtual model is configured such that at least onetooth is part of a removable component of the virtual model, the methodcomprising: obtaining a virtual model of the set of teeth, the virtualmodel comprising a gingival part and the at least one tooth which ispart of the removable component in the virtual model, the at least onetooth being removable in a longitudinal direction of the at least onetooth; generating a cavity in said gingival part, said cavity comprisinga cavity wall, into which cavity the removable component fits such thatan interface between the removable component and the cavity wall isdefined, where the removable component and the cavity are configured toprovide a gap at said interface, the gap extending circumferentiallyabout a portion of the removable component in a direction perpendicularto the longitudinal direction; and providing supporting elementsconfigured for supporting and positioning the removable component in thecavity, where the supporting elements extend in the longitudinaldirection on one of said removable component and said cavity wall suchthat the supporting elements extend across said gap between saidremovable component and said cavity wall, such that in the physicalmodel manufactured from the virtual model, the supporting elementssupport and position the removable component in the cavity; wherein, inat least one cross section taken through the removable component and thegap in a direction perpendicular to the longitudinal direction, contactbetween the removable component and the cavity wall at said interface isprovided only by surfaces of the supporting elements and the other ofthe removable component and the cavity wall such that, in the at leastone cross section, the gap extends only between the surfaces of thesupporting elements.
 2. The method according to claim 1, wherein atleast part of said supporting elements are generated on the removablecomponent such that an area of contact between the removable componentand the cavity wall at said interface is controlled by a shape ofadjoining surfaces of the supporting elements and the cavity wall. 3.The method according to claim 1, wherein at least part of saidsupporting elements are generated on the cavity wall such that an areaof contact between the removable component and the cavity wall at saidinterface is controlled by a shape of adjoining surfaces of thesupporting elements and the removable component.
 4. The method accordingto claim 1, wherein the supporting elements comprise one or morefriction points providing friction between the removable component andthe cavity.
 5. The method according to claim 1, wherein the supportingelements are arranged in positions corresponding to each straight sideof a base of the removable component.
 6. The method according to claim1, wherein a width of said supporting element in an area of contactbetween the supporting elements and the other of the removable componentand the cavity wall is in the range of 0.01 mm to 4 mm.
 7. The methodaccording to claim 1, wherein a length of said supporting element in anarea of contact between the supporting elements and the other of theremovable component and the cavity wall is in the range of 0.01 mm to 20mm.
 8. The method according to claim 1, wherein the height of thesupporting elements is in the range of 0.05 mm to 2 mm.
 9. The methodaccording to claim 1, wherein a number N_(elem) of supporting elementsare provided on the removable component and/or the cavity wall, whereN_(elem) is selected from the group of 3, 4, 6, 8, 9, 10, 12 or
 16. 10.The method according to claim 1, wherein a ratio between an area ofcontact between the supporting elements and the other of the removablecomponent and the cavity wall and an area of said cavity wall or a ratiobetween the area of contact and an area of said interface is below 0.9.11. The method according to claim 1, wherein the supporting elements areformed as cut-off pyramids or as square frusta or rectangular frusta.12. The method according to claim 1, wherein the supporting elements areconfigured to provide that their volume overlap at least partly with avolume of the removable component or the cavity wall when the removablecomponent is arranged in the cavity, such that a tight fit is createdbetween the cavity and the removable component.
 13. The method accordingto claim 1, where a contour of the cavity wall follows an outer curveand the contour of the removable component follows an inner curve, wherethe inner curve is arranged inside the outer curve.
 14. The methodaccording to claim 13, wherein supporting elements generated on saidremovable component comprise a surface in an area of contact between thesupporting elements and the other of the removable component and thecavity wall, which surface is aligned with the outer curve, such thatthese supporting elements are shaped to have a surface in the area ofcontact which is parallel to a surface of the cavity wall at the area ofcontact.
 15. The method according to claim 13, wherein supportingelements are generated on the wall of said cavity and comprise a surfacein an area of contact between the supporting elements and the other ofthe removable component and the cavity wall, which surface is alignedwith the inner curve, such that these supporting elements are shaped tohave a surface in the area of contact which is parallel to a surface ofthe removable component at the area of contact.
 16. The method accordingto claim 1, wherein said providing a virtual model comprises generatingsaid virtual model from a virtual representation of the set of teeth,and wherein the virtual representation of the set of teeth is providedby scanning the set of teeth by means of an intraoral scanner orscanning an impression of the set of teeth.
 17. The method according toclaim 1, wherein the method comprises digitally repositioning thegingival part of the model around the removable component, beforemanufacturing the physical model.
 18. The method according to claim 17,wherein digitally repositioning the gingival part of the model comprisesdigitally moving the gingival part of the model away from the removablecomponent.
 19. A system for generating a virtual model of a set of teethfor manufacturing a physical model of the set of teeth, where the systemcomprises a processor configured for: generating a virtual model of theset of teeth, where the virtual model is based on a virtualrepresentation of the set of teeth; providing that at least one tooth isconfigured to be arranged as part of a removable component in thevirtual model, where the removable component is adapted to fit into acorresponding cavity in a gingival part of the virtual model such thatan interface between the removable component and a wall of the cavity isdefined, where the removable component and the cavity are configured toprovide a gap at said interface, the at least one tooth being removablein a longitudinal direction of the at least one tooth, and the gapextending circumferentially about a portion of the removable componentin a direction perpendicular to the longitudinal direction; providingsupporting elements extending in the longitudinal direction forsupporting and positioning the removable component in its correspondingcavity, where the supporting elements are provided on one of saidremovable component and said cavity wall such that the supportingelements extend across said gap between said removable component andsaid cavity wall; and configuring the supporting elements such that, inat least one cross section taken through the removable component and thegap in a direction perpendicular to the longitudinal direction, contactbetween the removable component and the cavity wall at said interface isprovided only by surfaces of the supporting elements and the other ofthe removable component and the cavity wall such that, in the at leastone cross section, the gap extends only between the surfaces of thesupporting elements.
 20. A method of generating a virtual model of a setof teeth for manufacturing a physical model of the set of teeth, whereat least one tooth of the manufactured physical model is part of aremovable component which is removable in a longitudinal direction ofthe at least one tooth, the method comprising: obtaining a virtual modelof the set of teeth, the virtual model of the set of teeth comprising agingival part and the at least one tooth; generating a virtual model ofthe removable component comprising the at least one tooth; generating insaid gingival part a cavity comprising a cavity wall, into which cavitythe virtual model of the removable component fits with a gap such thatan interface between the removable component and the cavity wall isdefined, the gap extending circumferentially about a portion of thevirtual model of the removable component in a direction perpendicular tothe longitudinal direction; and providing virtual supporting elements tothe cavity wall, the virtual supporting elements extending in thelongitudinal direction, where the supporting elements in themanufactured physical model support and position the removable componentin the cavity, and in at least one cross section taken through theremovable component and the gap in a direction perpendicular to thelongitudinal direction, contact between the removable component and thecavity wall at said interface is provided only by surfaces of thesupporting elements and the removable component such that, in the atleast one cross section, the gap extends only between the surfaces ofthe supporting elements.
 21. A method of generating a virtual model of aset of teeth for manufacturing a physical model of the set of teeth,where at least one tooth of the manufactured physical model is part of aremovable component which is removable in a longitudinal direction ofthe at least one tooth, the method comprising: obtaining a virtual modelof the set of teeth, the virtual model of the set of teeth comprising agingival part and the at least one tooth; generating a virtual model ofthe removable component comprising the at least one tooth; generating insaid gingival part a cavity comprising a cavity wall, into which cavitythe virtual model of the removable component fits with a gap such thatan interface between the removable component and the cavity wall isdefined, the gap extending circumferentially about a portion of thevirtual model of the removable component in a direction perpendicular tothe longitudinal direction; and providing virtual supporting elements tothe portion of the removal component at the interface, the virtualsupporting elements extending in the longitudinal direction, where thesupporting elements in the manufactured physical model support andposition the removable component in the cavity, and in at least onecross section taken through the removable component and the gap in adirection perpendicular to the longitudinal direction, contact betweenthe removable component and the cavity wall at said interface isprovided only by surfaces of the supporting elements and the cavity wallsuch that, in the at least one cross section, the gap extends onlybetween the surfaces of the supporting elements.
 22. A method ofgenerating a virtual model of a set of teeth for manufacturing aphysical model of the set of teeth, where at least one tooth of themanufactured physical model is part of a removable component which isremovable in a longitudinal direction of the at least one tooth, themethod comprising executing computer program code on a data processingsystem, where the computer program code when executed causes the dataprocessing system to: obtain a virtual model of the set of teeth;generate a virtual model of the removable component from the virtualmodel of the set of teeth, where the virtual model of the removablecomponent comprises the at least one tooth; generate a cavity in thevirtual model of the set of teeth, the cavity comprising a cavity wall;where the virtual model of the removable component fits into the cavitywith a gap between the removable component and the cavity wall, the gapextending circumferentially about a portion of the virtual model of theremovable component in a direction perpendicular to the longitudinaldirection; and generating one or more supporting elements on the virtualmodel of the removable component and/or on the cavity wall, saidsupporting elements extending across the gap such that contact betweenthe removable component and the cavity wall at said interface isprovided only by the supporting elements such that, in the at least onecross section, the gap extends only between the supporting elements.